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Subject[PATCH v7 4/4] mm/hwpoison: introduce per-memory_block hwpoison counter
Date
From: Naoya Horiguchi <naoya.horiguchi@nec.com>

Currently PageHWPoison flag does not behave well when experiencing memory
hotremove/hotplug. Any data field in struct page is unreliable when the
associated memory is offlined, and the current mechanism can't tell whether
a memory block is onlined because a new memory devices is installed or
because previous failed offline operations are undone. Especially if
there's a hwpoisoned memory, it's unclear what the best option is.

So introduce a new mechanism to make struct memory_block remember that
a memory block has hwpoisoned memory inside it. And make any online event
fail if the onlining memory block contains hwpoison. struct memory_block
is freed and reallocated over ACPI-based hotremove/hotplug, but not over
sysfs-based hotremove/hotplug. So the new counter can distinguish these
cases.

Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
---
ChangeLog v6 -> v7:
- remove 'extern' in declarations of num_poisoned_pages_{inc,sub}
because they are not necessary and definition have 'inline'.
- remove unneeded declaration of memblk_nr_poison_{inc,sub}.

ChangeLog v5 -> v6:
- fix build errors over memblk_nr_poison_inc() and memblk_nr_poison_sub(),
- pass "struct memory_block *" to memblk_nr_poison() instead of pfn,
- removed clear_hwpoisoned_pages() and call num_poisoned_pages_sub() directly.
- add static keyword to the definition of memblk_nr_poison().
- Mioahe added Reviewed-by for v5, but I have some non trivial changes in
v6, so let me hold to add it.
- unpoison_memory() properly cancels per-memblk hwpoison counter.

ChangeLog v4 -> v5:
- add Reported-by of lkp bot,
- check both CONFIG_MEMORY_FAILURE and CONFIG_MEMORY_HOTPLUG in introduced #ifdefs,
intending to fix "undefined reference" errors in aarch64.

ChangeLog v3 -> v4:
- fix build error (https://lore.kernel.org/linux-mm/202209231134.tnhKHRfg-lkp@intel.com/)
by using memblk_nr_poison() to access to the member ->nr_hwpoison
---
drivers/base/memory.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/memory.h | 3 +++
include/linux/mm.h | 20 +++++++++++++++++++-
mm/internal.h | 8 --------
mm/memory-failure.c | 36 +++++++++++-------------------------
mm/sparse.c | 2 --
6 files changed, 71 insertions(+), 36 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 9aa0da991cfb..fe98fb8d94e5 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -175,6 +175,15 @@ int memory_notify(unsigned long val, void *v)
return blocking_notifier_call_chain(&memory_chain, val, v);
}

+#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_MEMORY_HOTPLUG)
+static unsigned long memblk_nr_poison(struct memory_block *mem);
+#else
+static inline unsigned long memblk_nr_poison(struct memory_block *mem)
+{
+ return 0;
+}
+#endif
+
static int memory_block_online(struct memory_block *mem)
{
unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
@@ -183,6 +192,9 @@ static int memory_block_online(struct memory_block *mem)
struct zone *zone;
int ret;

+ if (memblk_nr_poison(mem))
+ return -EHWPOISON;
+
zone = zone_for_pfn_range(mem->online_type, mem->nid, mem->group,
start_pfn, nr_pages);

@@ -864,6 +876,7 @@ void remove_memory_block_devices(unsigned long start, unsigned long size)
mem = find_memory_block_by_id(block_id);
if (WARN_ON_ONCE(!mem))
continue;
+ num_poisoned_pages_sub(-1UL, memblk_nr_poison(mem));
unregister_memory_block_under_nodes(mem);
remove_memory_block(mem);
}
@@ -1164,3 +1177,28 @@ int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
}
return ret;
}
+
+#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_MEMORY_HOTPLUG)
+void memblk_nr_poison_inc(unsigned long pfn)
+{
+ const unsigned long block_id = pfn_to_block_id(pfn);
+ struct memory_block *mem = find_memory_block_by_id(block_id);
+
+ if (mem)
+ atomic_long_inc(&mem->nr_hwpoison);
+}
+
+void memblk_nr_poison_sub(unsigned long pfn, long i)
+{
+ const unsigned long block_id = pfn_to_block_id(pfn);
+ struct memory_block *mem = find_memory_block_by_id(block_id);
+
+ if (mem)
+ atomic_long_sub(i, &mem->nr_hwpoison);
+}
+
+static unsigned long memblk_nr_poison(struct memory_block *mem)
+{
+ return atomic_long_read(&mem->nr_hwpoison);
+}
+#endif
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 463662ef7614..31343566c221 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -84,6 +84,9 @@ struct memory_block {
unsigned long nr_vmemmap_pages;
struct memory_group *group; /* group (if any) for this block */
struct list_head group_next; /* next block inside memory group */
+#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_MEMORY_HOTPLUG)
+ atomic_long_t nr_hwpoison;
+#endif
};

int arch_get_memory_phys_device(unsigned long start_pfn);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 278e24a0e3d3..816f566847e4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3248,7 +3248,8 @@ extern int soft_offline_page(unsigned long pfn, int flags);
#ifdef CONFIG_MEMORY_FAILURE
extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
bool *migratable_cleared);
-extern void num_poisoned_pages_inc(unsigned long pfn);
+void num_poisoned_pages_inc(unsigned long pfn);
+void num_poisoned_pages_sub(unsigned long pfn, long i);
#else
static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
bool *migratable_cleared)
@@ -3259,6 +3260,23 @@ static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
static inline void num_poisoned_pages_inc(unsigned long pfn)
{
}
+
+static inline void num_poisoned_pages_sub(unsigned long pfn, long i)
+{
+}
+#endif
+
+#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_MEMORY_HOTPLUG)
+extern void memblk_nr_poison_inc(unsigned long pfn);
+extern void memblk_nr_poison_sub(unsigned long pfn, long i);
+#else
+static inline void memblk_nr_poison_inc(unsigned long pfn)
+{
+}
+
+static inline void memblk_nr_poison_sub(unsigned long pfn, long i)
+{
+}
#endif

#ifndef arch_memory_failure
diff --git a/mm/internal.h b/mm/internal.h
index 4b44ced87fff..cb4c663a714e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -708,14 +708,6 @@ extern u64 hwpoison_filter_flags_value;
extern u64 hwpoison_filter_memcg;
extern u32 hwpoison_filter_enable;

-#ifdef CONFIG_MEMORY_FAILURE
-void clear_hwpoisoned_pages(struct page *memmap, int nr_pages);
-#else
-static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
-{
-}
-#endif
-
extern unsigned long __must_check vm_mmap_pgoff(struct file *, unsigned long,
unsigned long, unsigned long,
unsigned long, unsigned long);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 527ee0867742..3389dce6966e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -77,11 +77,14 @@ static bool hw_memory_failure __read_mostly = false;
inline void num_poisoned_pages_inc(unsigned long pfn)
{
atomic_long_inc(&num_poisoned_pages);
+ memblk_nr_poison_inc(pfn);
}

-static inline void num_poisoned_pages_sub(unsigned long pfn, long i)
+inline void num_poisoned_pages_sub(unsigned long pfn, long i)
{
atomic_long_sub(i, &num_poisoned_pages);
+ if (pfn != -1UL)
+ memblk_nr_poison_sub(pfn, i);
}

/*
@@ -1712,6 +1715,8 @@ static unsigned long __free_raw_hwp_pages(struct page *hpage, bool move_flag)

if (move_flag)
SetPageHWPoison(p->page);
+ else
+ num_poisoned_pages_sub(page_to_pfn(p->page), 1);
kfree(p);
count++;
}
@@ -2339,6 +2344,7 @@ int unpoison_memory(unsigned long pfn)
int ret = -EBUSY;
int freeit = 0;
unsigned long count = 1;
+ bool huge = false;
static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);

@@ -2387,6 +2393,7 @@ int unpoison_memory(unsigned long pfn)
ret = get_hwpoison_page(p, MF_UNPOISON);
if (!ret) {
if (PageHuge(p)) {
+ huge = true;
count = free_raw_hwp_pages(page, false);
if (count == 0) {
ret = -EBUSY;
@@ -2402,6 +2409,7 @@ int unpoison_memory(unsigned long pfn)
pfn, &unpoison_rs);
} else {
if (PageHuge(p)) {
+ huge = true;
count = free_raw_hwp_pages(page, false);
if (count == 0) {
ret = -EBUSY;
@@ -2421,7 +2429,8 @@ int unpoison_memory(unsigned long pfn)
unlock_mutex:
mutex_unlock(&mf_mutex);
if (!ret || freeit) {
- num_poisoned_pages_sub(pfn, count);
+ if (!huge)
+ num_poisoned_pages_sub(pfn, 1);
unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
page_to_pfn(p), &unpoison_rs);
}
@@ -2616,26 +2625,3 @@ int soft_offline_page(unsigned long pfn, int flags)

return ret;
}
-
-void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
-{
- int i, total = 0;
-
- /*
- * A further optimization is to have per section refcounted
- * num_poisoned_pages. But that would need more space per memmap, so
- * for now just do a quick global check to speed up this routine in the
- * absence of bad pages.
- */
- if (atomic_long_read(&num_poisoned_pages) == 0)
- return;
-
- for (i = 0; i < nr_pages; i++) {
- if (PageHWPoison(&memmap[i])) {
- total++;
- ClearPageHWPoison(&memmap[i]);
- }
- }
- if (total)
- num_poisoned_pages_sub(0, total);
-}
diff --git a/mm/sparse.c b/mm/sparse.c
index e5a8a3a0edd7..2779b419ef2a 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -926,8 +926,6 @@ void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
unsigned long nr_pages, unsigned long map_offset,
struct vmem_altmap *altmap)
{
- clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
- nr_pages - map_offset);
section_deactivate(pfn, nr_pages, altmap);
}
#endif /* CONFIG_MEMORY_HOTPLUG */
--
2.25.1
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